UPDATE,
Well after reading the codes via a paperclip test and failing to show any codes it finally got plugged into a tech 2 at my buddys dealership, again no codes stored and nothing showing of any concern on the live data whilst the engine was running with the aid of a little throttle. Plenun removed again and intake removed to check again for any spilit pipes and hoses including the brake servo pipe, all good. Replaced the icv valve rubber holder and plenum seal as i had bought it to replace a sloppy fit but no change in symptoms, wont idle when hot.
So decided to change the crank sensor with a new gen vx part fron vx, fitted said part and the car is now cured, idle rock solid for over an hour, so happy that it was the CS.
Seems i have found a new symptom of failing CS to add to the others that are known about.
VERY happy bunny.
Gary.